The paranasal sinuses are air-filled cavities within the facial skeleton. Each paranasal sinus is contiguous with a nasal cavity and drains into the nose through a sinus ostium. Although other factors may be involved, the development of sinusitis (inflammation of the mucosal lining of the sinuses) is most often attributed to blockage of one or more of these sinus ostia, followed by mucostasis and microbial overgrowth in the sinus cavity. Ostial blockage may stem from predisposing anatomical factors, or inflammation and edema of the mucous lining in the area of the ostia, arising from such etiologies as viral or bacterial upper respiratory infection or chronic allergic processes.
Traditionally, sinusitis has been medically managed by the oral administration of antibiotics and steroids. However, penetration of these systemically delivered agents into the sinus mucosa is limited due to poor blood flow to the sinuses. Therapeutic agents contained in aqueous solutions, creams, or gels, for topical application in the nose have also been formulated, but usually never travel far enough into the nose to reach the sinuses, are blocked from entering the sinuses due to obstructed ostia, or have such short contact with the sinus mucosa that absorption of the agent is low. For similar reasons, nasally inhaled steroid and anti-infective aerosols that have been developed to treat sinusitis are equally ineffective.
The delivery of ampicillin from a poly(lactic-co-glycolic)acid (PLGA) film to increase residence time of the antibiotic in rabbit sinuses has been investigated for the treatment of sinusitis (Min et al. Mucociliary Activity and Histopathology of Sinus Mucosa in Experimental Maxillary Sinusitis: A Comparison of Systemic Administration of Antibiotic and Antibiotic Delivery by Polylactic Acid Polymer. Laryngoscope 105:835-342 (1995) and Min et al. Application of Polylactic Acid Polymer in the Treatment of Acute Maxillary Sinusitis in Rabbits. Acta Otolaryngol 115:548-552 (1995)). Although clinical signs of sinusitis improved, the procedure for placing the film required that a hole be drilled through the anterior wall of the maxillary sinus.
Consequently, a biodegradable implant for administering a sustained release therapeutic agent to the paranasal sinuses for a prolonged time period without being substantially cleared by the mucociliary lining of the sinuses, and methods for delivering the implant in a minimally invasive fashion may provide significant medical benefit for patients afflicted with sinusitis.